1. Field of the Invention
The present invention generally relates to a culture vessel which is used for microorganism culture, cell culture, tissue culture and the like and, more particularly, to the structure of the neck constituting its opening part.
2. Description of the Prior Art
Conventionally, in the culture vessel with a cap on the neck, it is commonly known that the opening parts are round or of circular cross-section at the opening end A of the neck C and at the connecting part B joining the body D with the neck C respectively, and these opening parts have almost the same inner diameters, as illustrated in FIGS. 5, 6A and 6B (For example, U.S. Pat. No. Des. 285725). This form of the neck which has a straight pipe-shaped opening part has been used since early times, no matter whether the flask was made of glass or of synthetic resins. However, the limit of the opening areas of the opening end A and the connecting part B has caused the inconveniences enumerated hereinafter. That is to say, when an attempt to enlarge the respective opening areas at the opening end A and the connecting part B is made, the height of the entire culture vessel is increased making the form of the vessel unstable, and this gives rise to the defect that the vessels can not be stacked one on top of another, although such operations as introducing culture solution, inserting the pipette or the like may be easily practiced. On the other hand, when an attempt is made to decrease the diameter of the opening end A and the connecting part B respectively or to increase the length of the neck C with a view to making the form of the vessel stable and to facilitating piling up of the vessels, it becomes very inconvenient to perform the abovementioned operations and this gives rise to the defect that a dead angle appears during reagent sprinkling to the culture area or sucking of the cells from the culture area.
The above-mentioned defects are caused no matter whether the culture vessel is made of glass or of synthetic resins, and up to the present there have been no culture vessels having the form and structure which are evaluated as the most suitable ones.